package com.wifiunion.zmkm.utils;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import android.app.Activity;

public class SimpleCrypto extends Activity
{
    public static String encrypt(String seed, String cleartext)
            throws Exception
    {
        // byte[] rawKey = getRawKey(seed.getBytes());
        // byte[] hotelpwd = new byte[16];
        byte[] result = encrypt(seed.getBytes(), cleartext.getBytes());
        return toHex(result);
    }

    public static byte[] encrypt_byte(byte[] seed, byte[] cleartext)
            throws Exception
    {
        // byte[] rawKey = getRawKey(seed);
        // byte[] hotelpwd = new byte[16];
        byte[] result = encrypt(seed, cleartext);
        return result;
    }

    public static byte[] decrypt_byte(byte[] seed, byte[] cleartext)
            throws Exception
    {
        // byte[] rawKey = getRawKey(seed);
        // byte[] hotelpwd = new byte[16];
        byte[] result = decrypt(seed, cleartext);
        return result;
    }

    public static String decrypt(String seed, String encrypted)
            throws Exception
    {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    private static byte[] getRawKey(byte[] seed) throws Exception
    {
        KeyGenerator kgen = KeyGenerator.getInstance("AES/ECB/PKCS5Padding");
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
        sr.setSeed(seed);
        kgen.init(128, sr); // 192 and 256 bits may not be available
        SecretKey skey = kgen.generateKey();
        byte[] raw = skey.getEncoded();
        return raw;
    }

    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception
    {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES/ECB/PKCS5Padding");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    private static byte[] decrypt(byte[] raw, byte[] encrypted)
            throws Exception
    {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }

    public static String toHex(String txt)
    {
        return toHex(txt.getBytes());
    }

    public static String fromHex(String hex)
    {
        return new String(toByte(hex));
    }

    public static byte[] toByte(String hexString)
    {
        int len = hexString.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++)
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
                    16).byteValue();
        return result;
    }

    public static String toHex(byte[] buf)
    {
        if (buf == null)
            return "";
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++)
        {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }

    private final static String HEX = "0123456789ABCDEF";

    private static void appendHex(StringBuffer sb, byte b)
    {
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }

    /** Called when the activity is first created. */
    // byteתchar
    public static char[] getChars(byte[] bytes)
    {
        Charset cs = Charset.forName("ISO-8859-1");
        ByteBuffer bb = ByteBuffer.allocate(bytes.length);
        bb.put(bytes);
        bb.flip();
        CharBuffer cb = cs.decode(bb);

        return cb.array();
    }

    public static byte[] getBytes(char[] chars)
    {
        Charset cs = Charset.forName("ISO-8859-1");
        CharBuffer cb = CharBuffer.allocate(chars.length);
        cb.put(chars);
        cb.flip();
        ByteBuffer bb = cs.encode(cb);

        return bb.array();
    }

    public static byte[] intToBytes(int n)
    {
        String s = String.valueOf(n);
        return s.getBytes();
    }

}
